Method for manufacturing reflectors



R. N. CHU BB METHOD FOR MANUFACTURING REFLECTORS Jan. 25, 1927. 1,615,358

Filed August 25. 1924 Y 2 Sheets-Sheet 1 j! 61mm,

Jan. 25 1927.

R. N. CHUBB METHOD FOR MANUFACTURING REFLECTORS Filed August 25, 1924 2 Sheets-Sheet 2 Patented Jan. 25, 1927.

UNITED STATES PATENT OFFICE.

METHOD FOR MANUFACTURING REFLECTORS.

Application filed August 25, 1924. Serial No. 734,054.

This invention relates to the manufacture of polished reflectors, and pertains more particularly to a new, economical method for manufacturing headlight reflectors, as well as other reflectors for various purposes.

It will be understood, in the consideration of the invention, that the inner surface of a reflector, which is almost invariably concave in general form, must be provided with a highly reflective surface. In manufacture, the metal ofwhich the reflector is to be made is struck out of a flat sheet and drawn into form. Were the metal to be provided with a highly reflective finish before being shaped,

5 there would be no finish left by the time the reflector was shaped. The loss of finish would be due very largely tothe great distortion and displacement which takes place in metal during drawing and similar power press operations.

The principal object of the invention is to provide method and means whereby the metal of which a reflector is to be made may be finished first and shaped afterward without affecting the finish.

Another object of the invention is to provide for using metal whichhas a suitable stock finish, without damaging the finish.

Another object of the invention is 'to provide methods for manufacturing reflectors whereby the metal of which the reflector is made may be first blanked out in a flat shape, subsequently finished and polished and finally put through a shaping operation without destroying the finish.

It will be realized that the polishing of the inner surfaces of a concave reflector is a diflicult and costl task, whereas the act of polishing a flat lank of metal is quite in simple and inexpensive. The polishing is particularly costly in the cast of those types of reflectors which are polygonal on one or both dimensions; or, in other words, those reflectors which have a plurality of fiat surfaces arranged in a general parabolic arrangement. In such reflectors, it is particularly diflicult to finish the metal adjacent the intersections of the flat surfaces.

Another object of the invention is to pro- Vide a method for manufacturing any and all types of reflectors for any and all purposes regardless of whether the surfaces are to be dis osed on true curves, composite curves, theoretical parabolas, polygonal parabolas, or a combination of two or more 5 of the above.

Still other objects and advantages of my invention will appear hereinafter. I have illustrated by the accompanying drawings a preferred manner of carrying out my invention, and I have shown the invention applied to the manufacture of a reflector which s truly parabolic on one median line and polygonal on the other line, although it is anticipated that modified ways of carrying out the method will suggest themselves tothe minds of those skilled in the art, and. it will be obvious hereinafter that the method may be applied to the manufacture of any shape of reflector, or similar object whatso- 7 ever, and, therefore, it is to be understood that I am not to be confined to the specific method of manufacture about to be described or to the shape of reflector to which it is applied, and may alter the method and ap- 7 ply it to' the manufacture of any shape, within the appended claims.

In the said drawings Figure 1 is, a view in elevation of the blank Figure 2 is a plan view illustratin an intermediate 0 eration required in the b anking of some 0 the more difficult shapes of reflectors;

Figure 3 is a view of the finished blank;

Figure 4 is a view in section seen on a line 4-4 of Figure 3;

Figure 5 is a view in elevation of a form such as may be employed in carrying out my method;

Figure 6 is a view in enlarged detail section of the rim of a finished reflector;

Figure 7 is a view in section seen on'a line 7-7 of Figure 5;

Figure 8 is a view in front elevation of a 05 completed reflector.

In carrying out my improved method in the preferred manner, I provide the blank 1, which is preferably silvered and polished before any of the succeeding steps of manuloo facture are accomplished. In forming said blank, the usual lamp aperture 10 is rovided, this aperture being located slig tly above the true center of the blank.

Where metal is employed the upper sur- 1 face is silvered and polishe I have made the discovery, however, that a ver ood reflector may be made from celluloi w wk is silvered on the under side so that the finish is protected by the celluloid. The material used must of necessity be quite transparent. It will be apparent hereinafter that the method now being described is applicable to manufacturing reflectors from metal finished upon the upper side, or from a pliant translucent material silvered on the under side.

The reflector illustrated is that type which is parabolic on the vertical median line and parabolically polygonal on the transverse median line. The blank shown in Figure 3 is provided with a plurality of substantially vertical parallel slots 11,.11, etc., which increase in widthoutwardly as well as curving slightly outward. All slots terminate, as at 12, close to the transverse median line of the blank. The slots divide the blank into a plurality of strips 13, 13, etc., which are slightly connected to each other at points adjacent the transverse median line. The strips may be each and all made separate, but the act of assembling them and joining them together becomes more expensive. By leaving all the fingers connected to each other, the result is actually a single piece of metal.

By curving all the fingers or strips properly, the adjacent edges 14, 14, etc., may brought into juxtaposition, as will appear hereinafter.

Theoretically, at least, the slots should decrease in width inwardly and terminate at the true transverse medial line of the blank; if so, however, the fingers would be separated. However, I am able to approach the theoretical requirement very closely by continuing the slots quite close to the said medial line. Therefore, the slots should be of extremely minute diameter at their terminations, and it will be apparent to those skilled in the art of blanking sheet metal that a single die to make the blank 3 might be somewhat impractical to build and use.

Therefore the next most practical step in the operation is to provide the blank 2 with single'slots 15 made simply by shearingthe metal but without removing any metal.

' Then with the aid of a shear, such as 16,

metal 17, adjacent said. slot, may be cut away first from one side of the adjacent metal and then from the other side. The operation is illustrated particularly in Figure 2,

where I have shown the blank 2 undergoing the action of the shear. Thus the slots 11 are best formed and may be made to approach to extremely minute diameters at their terminations.

During the shearing operations there is ordinarily little or no tendency to mar the finish and there is no tendency to draw the metal sufiiciently to cause the finish to check or peel. However, if the metal or finish is such as to make it advisable, or if the manufacturer so desires, the plating and polishing of the blank may be done after it has reached the shape shown in Figure 3, in which case it is still flat and quite easy to plate and polish. The foregoing applies to metal or to silvered celluloid or the like.

To carry out the next step of my method, I employ a suitable form or block such as 20. This block is preferably made of suitable wood, or rubber or. other material not presenting a very hard surface to mar the polished surface of the reflector. In fact, very little efi'ort is required to form the blank to the required shape, and while I have shown the block 20 and other parts as of substantial weight such is done merely to illustrate the mode more clearly.

The blank 20, in making any size, type or form of reflector, should be the shape of the finished reflector ordinarily. Coacting with the forming block there is provided a die member 21. Said member is shown as quite substantial in construction to insure its hold ing its form indefinitely, but it is a fact that the blank 3 may be shaped over the block by the simplest of suitable means, even, in,

fact, by the human hand.

N ow the blank 3 is suitably arranged over the block and the die member is then moved b into place, as shown in Figure 7. N ow the Thereby the corresponding edges of adjacent strips are brought into contact with each other and the complete concave reflector is formed. While held over the form a metal binder 23 of U cross section may be shaped over the edges of the metal to pro.

vide a complete annulus or rim serving as a rim for the reflector and a permanent means of holding the metal in correct shape. During the act of bending the respective strips of metal, the finish will obviously be 11 harmed, it being known that highly plated and polished strips of metal may be bent into moderate curvatures many times without harming the surface, and the foregoing is applicable to all objects of a semi-spherical nature, and while I have shown the slots as being substantially parallel it will be apparent that a radial arrangement of slots, 7

as well as a great variety of other arrangements of slots, may be resorted to in the manufacture of various shapes of concave objects.

I claim as my invention:

1. Themethod for manufacturing a concave-convex object, of sheet material, said method including; providing a flat blank of sheet material with a plurality of slots intersecting the perimeter thereof, and ranging generally and normally to' said median line in both directions from the transverse 3' median line of the blank; said slots being of decreasing width inwardly and all terminating close to, and substantially equi-distant from, the transverse median line of the blank, and subsequently bringing opposed margins of each slot in to close proximity to each other.

2. The method for manufacturing a concavo-convex object, of sheet material, said method including; providing a flat blank of sheet material with a plurality of slots intersecting the perimeter thereof, and ranging generally and normally to said median line in both directions from the transverse median line of the blank; said slots being 1 a highly reflective surface, and subsequently 20 bringing the opposed margins of each slot into close proximity with each other.

RQVVLAN D N. CHUBB. 

